Centrifugal gaseous medium compressor

ABSTRACT

1,145,233. Shaft seals; pipe joints; toothed gearing. CHICAGO PNEUMATIC TOOL CO. 20 Oct., 1967 [30 Nov., 1966], No. 47854/67. Headings F2B, F2G and F2Q. [Also in Divisions F1 and F4].  Shaft seal.-A shaft sealing arrangement 97, Fig. 8, positioned between a centrifugal compressor stage impeller 87 and a hydrostatic bearing block 48, comprises a slinger disc 105 and a series of knife edges 107, 108, 109 which bite into a surrounding sleeve 113 of material such as plastics or fibre metal, which sleeve 113 forms a lining for a tube 114. Air leakage from the compressor is vented through a passage 115, vapours leaking from the bearing block are vented through a passage 117, and oil leakage from the bearing block is hurled outwardly by the slinger disc and flows through holes 104 into a chamber containing the driving gear of the compressor. Pipe coupling.-The discharge pipe 125, Fig. 14, of the compressor stage is connected to the inlet pipe 127 of an interstage cooler by a floating pipe section 126 comprising portions 136, 137 bolted together with their adjacent ends separated by a spacer 141 and gaskets 142. The remote ends of the portions 136, 137 are sealed within the pipes 125, 127 by 0-rings 139. Either portion 136 or 137 can be removed independently of the other after removal of the spacer 141. The pipe section 126 has a limited amount of end clearance to facilitate relative thermal expansion. Gearing.-Pinions 46, 46a, Fig. 5, carried by the shafts (not shown) of the centrifugal compressor stages, engage a driving bull gear 27 mounted on a shaft 28 journalled in hydrostatic bearings 35, 36. The compressor stage shafts are journalled in hydrostatic bearings arranged in a number of pairs of openings 52, 55. Oil leakage passing from the compressor stage bearings into the gear housing, lubricates the gears therein. The bull gear 27 is closely shrouded (e.g. with a clearance of approximately one-eighth of an inch) by a pair of baffle plates 29 to reduce windage.

Jan. 28, 1969 E. w. BLATTNER ETAL 3,424,372

I CENTRIFUC'AL GASEOUS MEDIUM COMPRESSOR Filed Nov. 30, 1966 Sheet of 8 Jan. 28, 1969 E. w. BLATTNER ETAL. 3,

CENTRIFUGALGASEOUS MEDIUM COMPRESSOR Filed NOV. 30, 1966 Sheet 3 of 8 Jan. 28, 1969 E. w. BLATTNER ETAL 3,424,372

CENTRIFUGAL GASEOUS MEDIUM COMPRESSOR I Sheet 3. of a Filed Nov. 30, 1966 Jan. 28, 1969 E. w. BLATTNER ETAL 3,424,372

CENTRIFUGAL GASEOUS MEDIUM COMPRESSOR Sheet Filed Nov. 30, 1966 Jan. 28, 1969 E. w. BLATTNER ETAL 3,424,372

CENTRIFUGAL GASEOUS MEDIUM COMPRESSOR I Filed Nov. 30, 1966 Sheet 5 of 8 FIG.

Jan. 28, 1969 E. w. BLATTNER ETAL 3,424,372

ENTRIFUGAL GASEOUS MEDIUM COMPRESSOR Sheet Filed Nov. 30, 1966 Jan. 28, 1969 E. w. BLATTNER ETAL.

ENTRIFUGAL GASEOUS MEDIUM COMPRESSOR Filed Nov. 30, 1966 Sheet Jan. 28, 1969 E. w. BLATTNER ETA... 3,424,372

V CENTRIFUGAL GASEOUS MEDIUM COMPRESSOR Filed Nov. 30, 1966- Sheet 8 of s I a; F/6./5 /68 i E /77 I me i United States Patent 3,424,372 CENTRIFUGAL GASEOUS MEDIUM COMPRESSOR Ernest W. Blattner, Franklin, Pa., Harry H. Boettcher,

Pleasantville, N.Y., Anthony F. Carter, Newton Highlands, and Arnold M. Heitmann, Swampscott, Mass., Wainwright Holt, Jr., Wyckotf, N.J., and David G. Wilson, Cambridge, Mass, assignors to Chicago Pneumatic gool Company, New York, N.Y., a corporation of New ersey Filed Nov. 30, 1966, Ser. No. 598,082 U.S. Cl. 230-127 17 Claims Int. Cl. F04d 17/08, 17/12, 29/58 ABSTRACT OF THE DISCLOSURE A compressor of the centrifugal type having a multiple number of compressor impeller assembly units, each directly driven by a common bull gear. It is suitable for the compression of air as avell as other gases. The compressor units which differ from one another in size are mounted in an orderly arrangement about one side of a common gear casing which houses the bull gear; and they are interconnected with one another by means of heat exchange units. Each compressor unit provides a separate stage of compression for the air drawn into it. The air drawn into each stage is efficiently compressed by its impeller through an individual diffuser unit and scroll into a separate one of the heat exchange units wherein it is cooled and freed of moisture before it is caused to be drawn into the next succeeding compressor unit for a further stage of compression. The air is finally discharged in a highly compressed condition from the final compressor unit.

This invention relates to the art of centrifugal gaseous medium compressors.

Multiple stage centrifugal compressors are known from United States Patent 3,001,692 to Schierl and the Swiss Patent 102,821 to Brown. These devices, however, do not obtain the advantages provided by the subject invention.

The nature of the compressor impeller assembly units is a principal feature of the apparatus. Each unit is a complete assembly or cartridge which is individually readiy attachable and removable as such relative to the common gear casing and to the bull gear without disturbing any of the other units. The unit is provided with an advantageous bearing and with a sealing arrangement whereby an impeller shaft of the unit is borne in the casing with a dual bearing support as it rotates and whereby the bearing fluid, and the air stream being actuated by the impeller, are prevented from contaminating one another.

Associated with each compressor unit is an improved diffuser unit having a group of turning vanes which cooperates with a group of diffusing vanes, whereby the air stream discharged from the impeller is slowed or guided to flow efficiently through a scroll.

A separate improved heat exchange unit or intercooler interconnects each compressor unit or stage with the next. Each unit may be readily assembled to or detached as a unit from the apparatus independently of the other units.

The several compressor impeller assembly units as well as the heat exchange units and interconnecting piping are all located and supported in an advantageous manner to one side of the common gear casing, whereby the load upon the casing and upon the general support of the apparatus is advantageously distributed. The piping connections between the heat exchange units and the 3,424,372 Patented Jan. 28, 1969 impeller assembly units are such that the approach for flow to the impellers is straight without bends.

Further, the heat exchange units are coupled to the scrolls associated with the compressor units by floating piping having a minimum of parts which may be readily assembled or disassembled without disturbing the related connected components.

As a consequence of the foregoing structure and the component members thereof an eflicient and practical improved centrifugal air compressor is provided which represents a decided advance in this art.

In the accompanying drawings:

FIG.'1 is a side elevational view of a four stage centrifugal air compressor illustrating the invention;

FIG. 2 is a top plan view of FIG. 1;

FIG. 3 is a left end elevation of FIG. 1;

FIG. 4 is an elevational view of the rear face of the gear casing, the compressor units being removed for clarity of illustration;

FIG. 5 is a section on line 5--5 of FIG. 4;

FIG. 6 is a section on line 66 of FIG. 4;

FIG. 7 is a sectional view of a compressor impeller assembly unit in association with the related scroll and the gear casing;

FIG. 8 is an enlarged section of the unit shown in FIG. 7;

FIG. 9 is a detail in section of the bearing block taken on line 99 of FIG. 11;

FIG. 10 is a right end elevational view of FIG. 9;

FIG. 11 is a left end elevational view of FIG. 9;

FIG. 12 is a detail in elevation of the diffuser unit;

FIG. 13 is an enlarged sectional view on line 1313 of FIG. 12;

FIG. 14 is an enlarged section on line 14--14 of FIG. 1;

FIG. 15 is a detail in side elevation of a heat exchange unit;

FIG. 16 is a rear elevational detail of the header of the heat exchange unit of FIG. 15; and

FIG. 17 is a rear elevational view of the heat exchange unit of FIG. 15.

The four-stage air compressor illustrated in the drawings includes a gear casing 20 serving as a common and direct support for the several stages, generally indicated in FIGS. 1 and 2 by the letters A, B, C and D and having correspondingly designated locationsin FIG. 4. The casing has at opposite peripheral areas a pair of foot flanges 21 each adapted to be bolted to a supporting base, such as a steel beam 22. The casing 20 (FIGS. 1, 4-6) is formed of a pair of opposed circular dished plates 23 and 24. The rear plate 23 has a peripheral bordering flange 25 which is rigidly bolted fluid-tight to a complementary flange 26 of the front plate 24. A large bull gear 27 is carried by a shaft 28 for rotation in the narrow chamber defined between the walls of the plates. A close clearance is maintained between the side areas of the gear and a pair of opposed circular baffle plates 29, one being mounted to each of the internal walls of the casing to reduce windage. A clearance of approximately one-eighth of an inch has been found conducive to good results.

The casing plates are strengthened by means of a ring of bosses 31 and 31a formed on the interior of the opposed casing plates in the area beyond the periphery of the bull gear; the bosses are bolted in face-to-face abutment. End portions 33 and 34 of the shaft are rotatably supported in a pair of suitable bearings such as hydrostatic oil bearings 35 and 36. Bearing 35 is fitted in the opening of an axially extending hub 37 of the front plate 24 and is retained in position by means of an external flange 38 bolted to the hub. The shaft end 33 extends extends externally of bearing 35; and it is adapted to be coupled to a suitable prime mover or motor, preferably a constant speed electric motor (not shown). The other bearing 36 is fitted in the opening of an axially extending hub 39 of the rear plate 23, and has an external flange 41 abutting the hub. A lube pump manifold 42 overlies flange 41; and the manifold and flange are bolted fast to the hub. A lube gear pump 43 carried by the shaft draws fluid lubricant through an inlet 44 of the manifold, and pumps it under pressure through an outlet 45 of the manifold to circulate it through a lube system, later to be described herein, to the various components of the apparatus. The hull gear 27 directly drivingly engages a separate pinion gear associated with each of the compressor stages A, B, C and D. The pinions 46 and 46a of stages A and D are shown in part in FIG. 5. It is understood that the number of compressor stages to be associated with the bull gear may vary.

Since the several stages are typical of one another or are of similar construction, except for size, only one of the stages is described in detail herein (FIGS. 7-11). The pinion 46 is carried by an impeller shaft 47 of the first compressor stage A. The impeller shaft is supported in a bearing means, here illustrated as a cylindrical stationary hydrostatic bearing block 48, for rotation on an axis parallel to that of the bull gear. The bearing block is bifurcated in its periphery 54 between its ends to provide an annular bifurcation or space 49 in which the pinion 46 is freely rotatable. The pinion projects radially out of the bifurcation sufficiently to engage the bull gear. At one side of the bifurcation the bearing block has a broad bearing end portion 51 of reduced diameter having a slide fit in an opening 52 of the front casing plate 24. At the opposite side of the bifurcation the bearing block has a second broad bearing portion 53 of greater diameter than the diameters of the bifurcated portion and of the reduced bearing portion 51. This large diameter bearing 53 has a slide fit in an opening 55 of the rear casing plate 23. The bearing block terminates adjacent the large bearing 53 in a radially extending circular flange 56, the inner face of which abuts upon the exterior face of the rear casing plate 23 and accordingly determines the extent to which the bearing block may be inserted into the casing openings 52 and 55. Flange 56 has a guide pin hole 57 in which a guide pin 58 projecting from the rear casing plate is received as a means of determining the proper angular position of the bearing block relative to the gear casing. The guide pin in cooperation with the guide pin hole locates the bearing block so that the open end of its bifurcation 49 overlies or spans the periphery of the bull gear 27 and so that the pinion 46 engages with the latter. The guide pin also restrains relative rotation between the bearing block and the gear casing. A nut 59 screwed upon a reduced terminal end of the impeller shaft holds a hydrostatic thrust collar 61 against a shoulder 62 of the impeller shaft; and a pin 63 prevents rotation of the collar relative to the shaft. The collar is positioned opposite the end face of the stationary bearing block. When the bearing block is seated in the openings 52 and 55 of the gear casing, the nut protrudes externally of the front plate 24. A crown cap 64 bolted to plate 24 protectively covers over the nut and thrust bearing.

The small bearing 51 of the bearing block has a plurality of circumferentially equally spaced radial lube holes 65, here four. Each hole communicates at its inner end with a separate internal lube cavity or pocket 66 of the bearing block overlying the impeller shaft. The several cavities are separated from one another by relatively narrow lands 67. An orifice 68 in each lube hole communicates with a common lube distribution channel or annulus 69 about the periphery of the bearing. Channel 69 registers with a lube passage 70 in the front casing plate 24. This passage in turn communicates through the interior of the plate with a port 71 in a supporting clamp 72 of one branch, generally indicated at 73 (FIGS. 4, 8) of a high pressure tubular lube assembly system. This branch line 73 is mounted about the interior wall of the front plate 24. The large bearing 53 of the bearing block has a similar group of radial lube holes 74, each similarly communicating at its inner end with a separate internal lube cavity 75 overlying the impeller shaft, the cavities being separated from one another by relatively narrow lands 76. Holes 74 are also fitted with orifices 77 having communication with a common peripheral lube distribution channel 78 registering with a lube passage 79 in the rear casing plate 23. Passage 79 communicates through the interior of the plate with a port 81 in a supporting clamp 82 of a second branch line 83 of the lube system. Branch line 83 is mounted about the interior surface of the rear plate 23. Each of the branch lube lines terminates in a separate feed port 84 or 84a, each having a pipe connection with the outlet 45 of the pump manifold. High pressure oil pumped into the branch lube lines 73 and 83 flows through the several lube holes 65 and 74 of the bearings to simultaneously fill the several related cavities 66 and 75 about the impeller shaft with pressurized fluid, causing the shaft to be hydraulically borne for rotation. At no time during rotation of the shaft is there any metal contact between the bearing block and the impeller shaft, since a film of oil at all times separates the shaft from the bearing block. A passage 85 in the small bearing 51 bleeds oil from the annulus 69 to the thrust collar 61 to provide an oil film between the bearing block and the thrust collar. Ports 86 extending through the thrust collar permit free fiow of oil about the latter.

An air compressor impeller 87 of the air inducing blade type is formed integral with the other end of the impeller shaft. The impeller is disposed externally of the gear casing plate 23. It operates in an individual impeller case 88 mounted by means of a ring of bolts 89' to the exterior of the gear casing plate 23. Air sucked in by the impeller through an inlet pipe 89 of a scroll 91 covering over the impeller case is compressively discharged through the periphery or exit end of the impeller into the volute 124 of the scroll.

Since the oil hydrostatically bearing the impeller shaft is under high pressure, some of it will bleed from the several cavities 66 and 75 through the normal slight clearance or looseness existing between the lands of the bearing block and the shaft. Some of this oil will bleed along the shaft into the bifurcation 49. This bled oil will eventually drip down about the bull gear 27 and over the bafiie plates 29 to the bottom of the gear casing from where it will be drained off to a sump through an outlet 93. Some of the oil bleeding along the impeller shaft into the clearances 94 adjacent the pinion 46 will be thrown by the shaft to the curved bottom of the bifurcation and splashed about to lubricate the pinion. Some of the oil will also bled from the bearing block along the shaft around the thrust collar and nut 59. An O-ring 95 between the end cap and the front casing plate will seal against leakage to the outside of the casing. Excess fluid collecting in the end cap will drain through axial ports 96 in the small bearing into the bifurcation.

Some of the oil fed to the bearing block 48 will also bleed around the shaft from the large bearing toward the impeller end of the shaft. An advantageous sealing arrangement, generally indicated at 97, is provided about the impeller shaft between the back of the impeller and the bearing block to prevent this oil from entering the impeller case and contaminating the air being compressed through the scroll. It also prevents the highly compressed air in the impeller case from leaking around the shaft and possibly adversely affecting the condition of the oil in the bearing block.

The sealing arrangement 97 includes a thick circular bafiie seal plate 98 having an axial opening 99 through which the impeller shaft extends. The baffle seal plate has a back face divided by an annular rib 101 into inner and outer annular surface areas. The outer area 102 serves as a mount, and is bolted flush upon a corresponding end face area of the flange 56 of the bearing block; and the inner area defines with an opposed slightly recessed central face area of the bearing block a narrow annular radial cavity 103 surrounding the impeller shaft. A group of axially extending drain holes 104 in the bearing block communicates this cavity with the bifurcation 49. Extending radially partway into this cavity while mantaining a slight clearance between the opposed walls of the cavity is a collar or oil slinger 105 defining one end of an anular seal 106. This seal is fitted fast upon the impeller shaft immediately to the back of the impeller. The seal has around its surface a plurality of parallel knife edges, here, arranged in three groups, designated 107, 108 and 109. The end groups 107 and 109 are spaced from the middle group 108 by means of peripheral channels or annuli 111 and 112. A liner 113, formed of abradable material having slight resilience of yieldability, such as Teflon plastic, fibre metal or material known by the trademark Feltmetal, is bonded to a tubular element 114 fitted fast in the axial opening 99 of the baffle seal plate. The liner bears upon the several knife edges; and is subject to being slightly grooved by the knife edges as the impeller shaft is rotated. Channel 111 of the seal registers with a radial vent passage 115 extending upwardly in order through the liner, the tubular element, the baffle seal plate and a hub collar 116 of the impeller case. The channel 112 registers with a second radial vent passage 117 extending downwardly in order through the liner, tubular element, the baflle seal plate and the hub collar 116.

The effect of the sealing arrangement 97 is to cause any high pressure air that might leak from the impeller case around the slight clearance normally existing at the back of the impeller through the tortuous passage provided by the knife edges and liner to the interseal annulus 111 to vent through passage 115; and to also cause any vapors that might escape from the bearing block through the tortuous passage provided by the seal collar and knife edges and liner to the interseal annulus 112 to vent through the vent passage 117. Oil bleeding from the bearing block to the radial cavity 103 will be centrifugally thrown or slung by the seal collar 105 into the drain holes 104 from Where it will drain through the bearing block to the bifurcation. A bevel 118 at the upper end of the cavity aids in deflecting into the drain holes 104 much of the oil tossed from the collar 105.

It is apparent that the several components surmounted upon the impeller shaft as above described define a cartridge or a compressor impeller assembly unit held together as such by means of the impeller 87 at one end of the impeller shaft and by means of the nut 59 at the other end. In making up the compressor assembly unit the bafile seal plate 98 is first fitted with the tubular element 114 containing the slightly resilient liner 113. The annular seal 106 is then inserted in the liner. In the later action, the liner yieldably expands to receive the seal and then retracts to press upon the knife edges of the inserted seal. Next, the bearing block 48 with the pinion 46 located in its bifurcation are assembled upon the shaft; and the flange 56 of the bearing block is then bolted to the baffie seal plate. The thrust collar 61 is next fitted onto the shaft. The entire assembly is then finally made secure upon the shaft between the impeller at on end and the nut 59 which is finally screwed into position on the opposite end of the shaft. This assembled unit defines a cartridge which may be packaged as such for ready assembly or replacement in the gear casing. This construction is of considerable advantage in the art of centrifugal compressors in that it enables the assembly to be slidably mounted in, or removed from, the casing as a cartridge or unit. It obviously saves considerable time in assembly, replacement and repair operations. After the impeller assembly unit has been properly positioned in the gear casing, it will be retained in its proper posi- .tion against endwise movement by means of the hub collar 116 of the subsequently mounted impeller case 88. The hub collar has a slidable sleeve fit over the peripheries of the bafile seal plate 98 and the flange 56 of the bearing block. Radial flange means 119 about the end of the hub collar is bolted by means of a ring of bolts 89 to the exterior of the rear casing plate 24. Cooperating shoulder means 121 of the hub collar and of the baffle seal plate restrain the compressor impeller assembly unit against axial movement away from the gear ease. The axial opening of the hub collar 116 is of greater diameter than that of the impeller, so that during assembly of the impeller case to the gear casing the hub collar may be passed freely over the impeller and sleeved upon the bafiie seal and flange plates 98 and 56.

The scroll cover 91 covering over the impeller case has an annular end flange 122 bolted to a complementary flange 123 of the impeller case. The scroll cover has a short axial inlet suction pipe 89 through which air is drawn by the rotating impeller into the impeller case; and it has an internal volute 124 ending in a short discharge pipe 125 (FIGS. 1, 2) through which the air is compressively discharged by the impeller. The discharge pipe is connected by means of a floating pipe coupling 126 (FIGS. 1, 14) to a short inlet pipe 127 of an intercooler or heat exchange unit 128. The intercooler serves to cool and dry the heated air discharged from the impeller preparatory to permitting it to flow to a succeeding stage for further compression.

A diffuser unit 129 (:FIGS. 7, l2, 13) is arranged about the periphery or exit end of the impeller 87 to diffuse the air stream leaving the impeller so as to cause it to flow smoothly and with reduced velocity through the scroll to be discharged into the related intercooler unit. Here, the diffuser comprises an annular flat plate 131 seated in a complementary recess 132 of the inner back wall of the impeller case. The plate has formed upon its open face a plurality of vanes in the form of long and short air-foils 133, 134. These lie in the narrow radial annular passage located about the peripheral exit end of the impeller and defined between the opposing walls of the scroll and the impeller case. The back wall of the scroll bears upon the outer surfaces of the vanes so as to restrain the diffuser in its seated condition. The vanes are arranged in two concentric rows; and the vanes in each row are spaced circumferentially similarly apart, whereby a plurality of passages or throats are provided across the face of the diffuser plate for the air stream leaving the impeller. The short vanes 134 occupying the inner row are disposed at an angle relative to the peripheral exit end of the impeller; and they have their leading edges in close proximity to the exit end of the impeller. The short vanes cause very little diffusion of the air leaving the impeller. They serve primarily to straighten out or turn the air stream toward the longer vanes so as to cause it to follow the long vanes.

The long vanes serve the usual function of diffusing the air stream leaving the impeller and providing a favorable passage for it into the scroll; whereas the short vanes have negligible diffusing effect and serve primarily to guide or bend the air stream favorably toward the diffuser vanes and the passages between them. The longer vanes are arranged at substantially the same angle as that of the shorter vanes, whereby the angle of air stream flow over the short and long vanes is substantially constant and favorable diffusion results are obtained. The outer row of long vanes are offset angularly a little from the inner row; so that the flow over the second row of vanes starts smoothly with substantially no attendant wake. The effect of the longer vanes is to substantially reduce the velocity of the air stream leaving the impeller and to convert it into pressure. Here, the long and short vanes are shown arranged at about 30 to the periphery of the impeller.

The floating coupling 126 (FIGS. 1, 14) is of decided advantage in the centrifugal compressor art. it enables the scroll cover 91 of the impeller case, and the related intercooler unit 128 to be coupled to one another or separately disassembled without disturbing the position or mounting of the other. It also has other apparent inherent advantages. The coupling includes a pair of similar pipe sections 136 and 137, each terminating in a radial flange 138 at one end; and each having an opposite free end provided with a peripheral groove in which is seated and O-ring seal 139. A pipe spacer 141 is disposed between the end flanges. The spacer, together with the pipe sections and intermediate sealing gaskets 142 are movably bolted to one another by means of a ring of bolts. The free end of pipe section 136 has a slide fit in the short discharge pipe 125 of the scroll cover; and it is limited in the extent to which it may be inserted by means of an internal shoulder 143 of the discharge pipe. The O-ring 139 seals the inserted pipe section fluid tight. The free end of the other pipe section 137 has a similar association with the short inlet pipe 127 of the intercooler unit. The overall length of the assembled coupling is a little shorter than the distance between the internal shoulders 143 of the discharge and inlet pipes so as to provide a desirable end clearance. This clearance permits a desirable limited axial floating movement of the coupling during operation of the apparatus to enable the coupling to move as needed with thermal expansion that may develop in the coupled components. This limited movement also enables assembly and disassembly of the coupling without disturbing either of the related coupled components. To assemble the coupling, each pipe section after having been first disconnected from the spacer 141 is inserted in its respective inlet or outlet pipe connection until limited by the related internal shoulder 143. When this is done, sufficient space will remain between the end flanges to allow the spacer and gaskets to be loosely assembled between them. The flanges, spacer and gaskets are then bolted and drawn tightly together. When disassembling the coupling, the spacer is first unbolted and, together with the gaskets is slipped free of the flanges. The resultant space developing between the flanges will be sufficient to allow the pipe sections to be axially withdrawn from their respective pipe connections. A special advantage of this arrangement is that the short coupling is the only piping required between the discharge end of the scroll and the inlet of the related intercooler unit.

The intercooler unit 128 (FIGS. 1-3 and 17) is also of decided advantage in this art. It includes a cylindrical can or shell 144 having a flange 145 about its open end which is removably bolted to a complementary flange 146 of a covering header 147. Disposed within the shell is a pair of heat exchangers or cooler units 148. These are of rectangular configuration, superimposed or stacked one above the other. Each cooler unit has a finned tubular core 149. The fins 151 are plates extending vertically from the rear to the front of the core; the tubes 152 of the core extend transversely through the fins and are fixed in a pair of end plates 153. A separate water jacket or manifold 154 is bolted over each end of the core. Each manifold has an identical pair of end mounting flanges 155, one flange of which has a passage 156 serving as an inlet for admitting fluid coolant through the manifold to the tubes of the finned core; and the other of which has a similarly located passage (not shown) serving as an outlet at the opposite end of the core for the coolant. The cooler units are individually supported by means of their flanges and bolts to the header 147.

The header 147 is a casting formed to guide with a minimum of interference the heated compressed air entering its inlet pipe 127 over the exterior of the cooler units to the rear of the shell. This air will then flow forwardly through the finned cores and finally exit through a discharge pipe 157 of the header. The header has an outer wall 158 of general cup-form. The wall of the discharge pipe 157 of the header continues as part of the casting for a short distance into the interior of the header to define the neck of a throat or duct 159 defined by an inner wall 161. The contoured wall of the throat diverges rearwardly in spaced relation to the outer wall and finally terminates at the rear of the header in a frame or grate defined by a group of ribs 162, 163. The several ribs 162, 163 define a squared central opening 164 into the throat. The several ribs extend in the manner of chords across the rear of the header. They are made integral at their ends with the outer wall of the header to provide a good support and rigidity for the rear of the inner wall 161. The ribs also define with the outer wall of the header a group of chord openings 165. The latter communicate with the common space or inlet duct 166 separating the inner and outer walls. This space conneets with the inlet pipe 127. The vertical chord ribs 163 are relatively broader than the others 162. They serve as supporting mounts to which the end flanges of the cooler units are removably bolted. A fluid coolant inlet port 167 in the header connected to the discharge end of a circulating pump (not shown) communicates through a passage 168 in one of the vertical ribs with a pair of ports 169, each registering with a separate one of the inlet ports 156 of the cooler units; and an exit port 171 at the opposite side of the header connected to the intake end of the coolant pump communicates through a similar passage 172 of the other vertical rib with a pair of ports 173, each registering with a separate outlet port (not shown) in the manifolds 154 (FIG. 17) at the right end of the cooler units.

The squared rear opening 164 of the header registers with the perimeter of the stacked cooler units 148. A baflle plate 174 abutting the end face of the upper rib 162 of the header overlies the core of the upper cooler unit and rests at its ends upon the top walls of the related end manifolds. Clamps 175 fastened to the manifolds retain the position of the baflle plate. A second baflie plate 176 is similarly disposed and retained relative to the underside of the lower cooler unit. By this arrangement the upper cooler unit is closed over at its top; the bottom cooler unit is closed over at its bottom; and the sides of both cooler units are closed over by their manifolds 154. Accordingly, both cooler units are uncovered only at their front and rear ends. The cooler units extend axially from their flanged mountings freely into the shell 144. The free space in the shell above, below, at the sides, and to the rear of the cooler units communicates with the chord openings of the header; and the interior of the shell communicates through the finned cores with the squared opening 164 of the header. Accordingly, it can be seen by this advantageous construction that heated compressed air entering the inlet pipe 127 will flow through the duct 166 defined between the inner and outer walls of the header to the chord openings 165. It will then be guided from the openings 165 by the battle plates and exterior surfaces of the manifolds over the exterior of the cooler units to the rear of the shell. The rear wall surface 177 of the shell will smoothly further guide the air stream forwardly through the finned cores to the squared opening 164 through which the cooled air will pass to the discharge pipe outlet. By this arrangement the air flow through the coolers is accompanied by a minimum of undesirable interference, and the air stream in passing through the finned cores traverses the full axial length of the walls of the fins. Moisture condensed out of the moving air drops to the bottom of the throat 159 where it is caught in a sump 178 and drained through an outlet 179.

The discharge pipe 157 of the intercooler unit is connected by means of a floating coupling 181 (FIG. 1), in the nature of the coupling 126 earlier described, with a short axial inlet suction pipe 182 in the scroll cover 183 of the impeller case of a second compressor stage B, similar to that just described, except for size.

The gear casing 20 is here designed to accommodate, as earlier mentioned, four compressor stages, one at each of the locations A, B, C and D (FIG. 4). Each is similar to that of the first, except for size. Each is similarly provided with a compressor impeller assembly unit or cartridge as that earlier described, which is similarly mountable in the gear casing for association of its pinion with the bull gear. The several stages are angularly positioned about the gear case, as indicated by their locations A, B, C and D, in desirable spaced relation to one another to fairly distribute their load upon the supporting gear casing. The air intake suction pipe 89 of the first or initial stage A is open to atmosphere for its source of air; whereas the intake suction pipe of each of the other stages is connected to the discharge pipe of a separate intercooler unit. This is a straight connection providing a straight approach for air to the impeller without bends. This leads to best flow conditions and high impeller efliciency. Further, the discharge pipe 184 of the final stage D does not connect with an intercooler. Accordingly, the apparatus comprises four stages of compression operating off a common driving gear, and three stages of cooling. The intercoolers of the several stages and their mode of connections to the several stages are similar to that already described. It is understood that the number of stages may be varied, and the gear casing may be varied in size accordingly.

The impeller 87 of the first stage A and its torque transmitting pinion 46 are larger than those of the other stages. The size of the impellers proportionately decreases with each suceeding compressor stage B, C and D in accordance with the state of the air being compressed. The sizes of the related pinions also progressively decrease so as to vary the speed of the impellers as needed. Accordingly, each stage is proportioned in size to the others. This arrangement enables the impeller of the first stage to operate at high speed to induce into its case a large volume of air. As this air progressively passes from stage to stage its pressure and density increases. The interconnecting piping between the scrolls and the intercoolers are also proportionately reduced in diameter as needed.

It is also to be noted that the impeller cases and the intercooler units with the interconnecting piping are all located to the same side of the gear casing. This is of decided advantage in that it provides for compactness. It also enables the use of relatively short interconnecting piping, thus reducing the overall air flow circuit and increasing the output efliciency of the overall apparatus. It is also to be noted (FIG. 3) that two of the intercoolers 128 and 185 (FIGS. 1-3) are supported by foot flanges 21a in side by side relation; and that one of the latter two intercoolers has a pair of upper side flanges 186 upon which corresponding flanges 187 of the third intercooler 188 are supported to provide a compact association of the three intercoolers. In this compact arrangement the gear casing 20' is centered substantially axially relative to the three intercoolers and is of such diameter that portions of the peripheral flanges 145 of all three intercoolers lie in opposed relation to portions of the border flanges 25, 26 of the gear casing so that tie-rods 189 extended from the casing to each of the intercooler units serve to strengthen components of the apparatus to one another. The tie-rods serve to reduce the load passing from the connecting piping of the intercoolers and the gear case to the flanged supporting feet 21, 21a of the apparatus.

The mounting arrangement of the compressor impeller assembly unit (FIGS. 7, 8) relative to the gear casing is also to be noted. Substantially the full support of the unit is transmitted through the bearin g block to the gear casing; and the bearing block provides a balanced load upon the casing, distributed substantially in equal degree through the bearing block to both plates of the gear casing.

Branch line 73 of the lube system serves to feed hydrostatic lube fluid to the small bearing of the bearing block of each of the compressor impeller assembly units mounted in the casing. This branch extends (FIGS. 4, 6) from its individual inlet port 84 at the gear casing and the coupling clamp block 72 in opposite directions to feed the several impeller units at locations A, B, C and D. The branch line is supported to the interior surface of the related gear casing plate 24. The other branch line 83 of the lube system serves to feed hydrostatic fluid to the large bearing portion of the bearing block of each of the compressor impeller assembly units; and it is similarly arranged about the interior of its related gear casing plate 23 and to its individual inlet feed port 84a.

It is to be further noted that the mounting arrangement of the intercooler units is such that they may be individually and without difficulty disconnected from the apparatus.

What is claimed is:

1. In a centrifugal gaseous medium compressor including a gear casing having opposed front and rear walls secured together to define a chamber between them, and a bull gear supported for rotation in the chamber, the casing being formed to provide an opening extending transversely of both walls of the casing having an axis parallel to that of the gear; the improvement comprising a compressor impeller assembly cartridge removably mounted as such to the casing including an impeller shaft, a bearing having a slide fit in the opening rotatably supporting the shaft in both walls and having a bifurcation between its ends, a pinion located in the bifurcation on the shaft having direct engagement with the bull gear, means determining the position of the bifurcation so that its bottom is above the pinion, and means for directing lubricant fluid along the shaft into the bifurcation at opposite ends of the pinion.

2. In a centrifugal gaseous medium compressor including a gear casing having opposed front and rear dished walls secured together to define a chamber between them, and a bull gear supported for rotation in the chamber, the casing being formed to provide a transverse opening having an axis parallel to that of the gear, the improvement being a compressor impeller assembly cartridge having a slide fit in the opening, the cartridge comprising: a shaft carrying an impeller at one end, hydrostatic bearing means supporting the shaft in the opening, a pinion on the shaft having direct engagement with the bull gear, mounting means removably mounting the cartridge to a wall of the gear casing, fluid sealing means between the impeller and one end of the hydrostatic bearing means, thrust means adjacent the other end of the hydrostatic bearing means, and a retaining nut on the shaft adjacent the thrust means.

3'. In a centrifugal gaseous medium compressor including a vertically split circular gear casing having opposed front and rear walls defining a chamber between them, a bull gear supported axially of the casing for rotation in the chamber, a bore of small diameter in the front wall at a level above the periphery of the bull gear, and a bore of larger diameter in the rear wall having an axis aligned with that of the small bore and parallel to that of the bull gear; a compressor impeller assembly unit comprising: a cylindrical hydrostatic oil bearing block having a bifurcation between its ends defining a pair of opposed bearings one larger in diameter than the other, the smaller one having a slide fit in the small bore, the larger having a slide fit in the large bore and the bifurcation spanning the bull gear, a radial flange terminating the large bearing abutting the exterior of the rear wall of the casing, an impeller shaft rotatably supported in the bearings carrying a compressor impeller at one end and projecting at its opposite end beyond the bearing block, thrust means retained on the projecting end having cooperation with the adjacent end of the block to prevent endwise escape of the shaft from the block, a baflle seal plate axially surrounding the shaft rearwar-dly of the impeller and abutting the flange, and a pinion carried by the shaft in the bifurcation having meshed engagement with the bull gear.

4. In a centrifugal gaseous medium compressor according to claim 3, wherein there is provided an impeller case in which the impeller is received removably mounted to the exterior of the rear wall of the gear casing having an abutment restraining the compressor impeller assembly unit against axial release in a rearward direction from the gear casing.

5. In a cenrtifgual gaseous medium compressor according to claim 3, wherein a guide pin projecting from the exterior of the rear wall of the gear casing is received in a complementary hole of the flange of the hearing block whereby the specific angular position of the bearing block to the gear casing and the bull gear is determined and the bearing block is restrained against relative rotation.

6. In a centrifugal gaseous medium compressor according to claim 3, including means for feeding highly pressurized lubricant radially through each of the hearings to the surface of the shaft, and sealing means between the impeller and the flange of the bearing block having a first stage providing a tortuous passage axially of the bafile seal plate terminating in a vent for air leaking from the impeller case around the shaft, and having a second stage passage adjoining the first stage providing a second tortuous passage axially of the baflle seal plate terminating in a further vent.

7. In a centrifugal gaseous medium compressor according to claim 6, wherein the sealing means comprises a tubular seal member fitted fast about the shaft axially of the baffle seal plate having a plurality of groups of parallel peripheral knife edges, each group being spaced from the other by an annulus, an abradable resilient tubular member seated fast in the battle seal plate sleeving over and bearing upon the knife edges, a vent passage extending upwardly through the baflle seal plate communicating through a hole of the tubular member with one of the annuli, and a second vent passage extending downwardly through the baffle seal plate communicating through a second hole of the tubular member with another annulus.

8. In a centrifugal gaseous medium compressor according to claim 6, wherein the lubricant feeding means includes a lube gear pump operable by the shaft of the bull gear having an inlet connection with a sump and an outlet connection with the bearings.

9. In a centrifugal gaseous medium compressor according to claim 6, wherein the bearing block has leakage around the shaft from both bearings into the bifurcation, and there being a clearance between the ends of the pinion and the opposing walls of the bifurcation permitting such leaking fluid to be centrifugally thrown by the shaft to the bottom of the bifurcation and as a consequence splashed about the pinion and bull gears.

10. In a centrifugal gaseous medium compressor according to claim 6, wherein a narrow radial cavity is defined about the shaft between the baffle seal plate and the bearing block having communication through a group of axial drain holes in the bearing block with the bifurcation, and a collar formed at one end of the tubular seal member rotates in this cavity causing lubricant leaking around the shaft from the large bearing to the cavity to be centrifugally thrown towards the end of the cavity, and inclined wall means is formed about the end of the cavity to deflect the thrown lubricant into the drain holes.

11. In a centrifugal gaseous medium compressor according to claim 4, including a scroll fitted to the impeller case defining with the impeller case an annular radial passage about a peripheral exit end of the impeller for conducting air flow discharged from the impeller into the scroll; air flow diffuser means comprising a flat annular plate seated in the radial passage in surrounding relation to the exit end of the impeller, an outer annular row of long air flow diffuser vanes arranged about a face of the plate each at a predetermined angle to the exit end of the impeller providing an angular succession of air fiow passages between the vanes across the face of the plate, and an inner annular row of relatively short air flow turning vanes having negligible air diffusing effect arranged about the face of the plate each at an angle to the exit end of the impeller corresponding substantially to that of the long vanes, the inner row of short vanes being offset angularly relative to the row of long vanes and having their leading edges in close predetermined spaced relation to the exit end of the impeller, the short vanes serving to turn the air stream leaving the impeller in the direction of the long vanes and the passages defined between the latter.

12. In a centrifugal gaseous medium compressor according to claim 11, wherein the long and short vanes are in the form of air-foils, and the air flow passages between the long vanes are each in extension of an angle corresponding substantially to the flow angle of the air stream at the exit end of the impeller.

13. In a centrifugal gaseous medium compressor according to claim 3, wherein the thrust means is a collar mounted upon the shaft having one face in opposed relation to the said end of the block, lube passage means is provided through the block to said face, and ports are provided through the collar communicating said one face with an opposite face of the collar.

14. In a centrifugal gaseous medium compressor according to claim 4, including a scroll fitted to the impeller case having an integral inlet suction pipe communicating with the impeller and an integral discharge pipe communicating through the scroll with the exit end of the impeller; an intercooler unit having an integral inlet pipe; and a floating coupling connecting the discharge pipe of the scroll with the inlet pipe of the intercooler unit, the coupling comprising a first pipe section slidably fitted at one end in the discharge pipe of the scroll including an O-ring seal having a sealing relation to the discharge pipe, a second similar pipe section having a similar arrangement in the inlet pipe of the intercooler unit, a flange terminating the other end of each pipe section, a spacer disposed between the flange, and fastening means removably securing the spacer and flanges together, the coupling having limited endwise floating movement relative to the discharge and inlet pipes, the overall distance between the flanges upon removal of the spacer being sufficient to permit axial withdrawal of either pipe section from the related pipe in which it has been inserted.

15. In a centrifugal gaseous medium compressor according to claim 4, including a scroll fitted to the impeller case having an inlet suction pipe communicating with the impeller and having a discharge pipe for discharging air leaving the impeller, and a heat exchange unit for receiving and cooling air discharged from the scroll, the heat exchange unit comprising: a cylindrical can open in its forward end, a cup-form header having a rear end detachably fastened over the open end of the can, an inlet pipe to the header, a grate formation at the rear of the header defining a large central opening and a plurality of ducts about the central opening all opening directly into the can, a common passage through the header communieating the plurality of ducts with the inlet pipe, a discharge pipe having communication with the central opening, and finned cooler means having an open front exit end registering with the central opening and having a rear entrance end, means removably fastening the cooler means to the grate formation, the cooler means extending axially from the grate formation into the can in spaced relation to the surrounding wall area of the can, plate means overlying the top, bottom and the side areas of the cooler means, and the fins of the cooler means being upright plates extending from the front to the rear, whereby air passing through the plurality of ducts of the grate formation flows over the plate means of the cooler means to the rear of the can and then flows through the cooler 13 means forwardly over the full length of the fin plates to the exit end thereof into the central opening to the discharge pipe.

16. In a centrifugal gaseous medium compressor according to claim 3, wherein a pair of baflle plates are arranged within the casing in close spaced relation to opposed faces of the body of the bull gear so as to reduce windage.

17. A centrifugal gaseous medium compressor comprising a gear casing having opposed dished front and rear walls secured about their marginal areas to one another defining a chamber between them, a bull gear supported axially of the casing for rotation in the chamber, a plurality of orderly arranged openings in the gear casing each in order having a proportioned size relation to the other, a separate impeller compressor assembly unit slidably fitted in each opening having an impeller shaft pinion disposed within the chamber in meshed engagement with the bull gear, a separate scroll housing removably mounted to the gear casing in association with a separate one of the impeller compressor assembly units for discharging air flow leaving the related impeller compressor unit, each scroll housing having an inlet suction pipe communicating axially with the related impeller compressor assembly unit and having a discharge pipe, a group of separate heat exchange units one less than the number of impeller compressor assembly units, each exchange unit having an inlet pipe and a discharge pipe, the inlet pipe of each heat exchange unit having a floating pipe coupling connection with the discharge pipe of a separate one of the scroll housings with the exception of the last in the order of the impeller compressor assembly units, and the discharge pipe of each heat exchange unit having a straight pipe connection axially with the inlet suction pipe of each of the scroll housings with the exception of that of the first in the order of the arrangement of the impeller compressor assembly units, and the impeller compressor assembly units having in the order of their arrangement a proportioned size relation to the others.

References Cited UNITED STATES PATENTS 2,695,131 11/1954 Price 230127 2,849,960 9/ 1958 Olmstead et al 103-111 3,001,692 9/ 1961 Schierl 230-209 3,079,605 2/ 1963 Thomas et a1. 103-111 3,174,680 3/1965 Young 103111 3,355,096 11/ 1967 Hornschuch 230129 FOREIGN PATENTS 940,931 3/ 1956 Germany.

971,224 7/ 1950 France. 1,285,760 1/ 1962 France. 1,336,834 7/ 1963 France.

317,623 1/ 1957 Switzerland.

HENRY F. RADUAZO, Primary Examiner.

US. Cl. X.R.

UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION Patent No. 3,424,372 January 28, 1969 Ernest W. Blattner et al,

It is certified that. error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 47, "read y" should read readily Column 2, line 72, cancel "extends". Column 5, line 10, "anular" should read annular line 56, "later" should read latter Column 7, line 9, "and" should read an Column 9, line -31, "suceeding" should read succeeding line 63, "strengthen components" should read strengthen the common support of the several components Column 11, line 9, "cenrtifugally" should read centrifugally Signed and sealed this 24th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER,

Attesting Officer Commissioner of Patents 

